I was just thinking, did new song books precede periods of JW doctrinal changes?
The latest songbook ( 2009 ) came out just before the maniacal rebranding of Watchtower into JW.'org.
What about previous generations? ( not overlapping )
When the last songbook ( 1984 ) arrived on the world scene ( I want this to sound dubby ) did it come before new and exciting revelations from the slave, that won't actually be appointed until after the great tribulation and not until they study the Feb 2017 WT, are not inspired...